A porous body is used in various applications, such as filters, cooling members, and muffling members. When a porous body is used as a filter, for example, the porous body filters or captures impurities contained in a fluid.
An airbag system is an example of a system that uses a porous body as a filter. The airbag system comprises an inflator (gas producing device) that produces gas by burning a powder. The airbag system is a system that inflates an airbag by supplying the gas produced by the inflator to an airbag incorporated into a steering wheel or the like. The porous body used in such an airbag system captures combustion remnants produced when the inflator burns the powder, cools the produced gas, and thus prevents the airbag from becoming damaged. Methods for manufacturing this porous body have been proposed in various literature to date.
The manufacturing method proposed in Patent Document 1 is a method for manufacturing a porous body from a wire mesh body formed by plain-knitting a metal wire. This manufacturing method comprises the steps of forming a preliminary tubular wire mesh body using a tubular wire mesh body formed by plain-knitting a metal wire, molding a small-diameter tubular wire mesh body obtained by reducing a diameter of this preliminary tubular wire mesh body by a drawing process, cutting the small-diameter tubular wire mesh body to a predetermined length, compressing the cut small-diameter tubular wire mesh body in a longitudinal direction and molding the wire mesh body into a cylindrical intermediary molded wire mesh body, and further compressing the cylindrical intermediary molded wire mesh body in the longitudinal direction and molding the wire mesh body into a cylindrical molded wire mesh body.
The manufacturing method proposed in Patent Document 2 comprises the steps of plain-knitting a metal wire to form a cylindrical wire mesh, forming a hollow cylindrical wire mesh body by winding a band-shaped body obtained by folding this wire mesh around a core member, and compressing this cylindrical wire mesh body by applying pressure from both sides in an axial direction thereof.